Our laboratory is engaged in electron microscopic and cytochemical studies designed to yield information concerning the structural and functional effects of vasectomy upon the seminiferous epithelium of the testis and upon the ducts of the male genital system. Research has been completed on regional alterations in morphology along the length of the vas deferens, and on the effect of vasectomy in dogs upon the vas itself, using various methods of vasectomy. Ongoing and proposed research includes cytochemical studies of the vas epithelium and seminiferous epithelium following long-term vasectomy. To be initiated are studies of protein absorption by the vas following vasectomy, and the effect of vasectomy upon the blood-testis barrier.